1. Field of the Invention
The present invention relates to a rotary position sensor, and more particularly, to the rotary position sensor suitable for an acceleration sensor for use in an automotive vehicle or the like.
2. Description of the Related Arts
Various types of rotary position sensors have been known heretofore, as in Japanese Utility Model No. 2586838, for example, which discloses a throttle position sensor having a base plate mounted in a housing spaced from a rotary member by a certain distance, with a detection circuit formed on a surface of the base plate, and connector terminals mounted in the housing, wherein the detection circuit is connected to the connector terminals through connecting terminals. The sensor includes a pair of engaging members formed in parallel with each other to provide a C-shaped plan view, between which end portions of the connector terminals are held and connected by resistance welding.
In Japanese Patent Laid-open Publication No. 8-285516, there is disclosed a rotating position detecting device for detecting an opening angle of a throttle valve or the like, wherein terminal plates, which correspond to the connector terminals, are fixed to a housing in a body through insert molding. Each terminal plate is made of a single plate bent by press working as shown in FIG. 2 of the Publication, and it includes an external terminal and a contact portion contacting with an end portion of a resistor circuit surface, and it is disposed in the housing under a resiliently deformed condition, to be pressed onto the end portion of the resistor circuit surface by the resilient force.
In the Utility Model No. 2586838 as described before, the throttle position sensor was proposed to improve a prior sensor which included a base plate having a detection circuit deposited thereon, whose connecting terminals were connected by resistance welding to connector terminals supported by a housing, with their surfaces mated with each other. The sensor was proposed in view of such problems that when the connecting terminals were connected to the connector terminals, the connecting surfaces of the terminals were hardly mated with each other. If one of the terminals were bent by accident, positioning of the terminals would be hardly achieved to cause a trouble in welding them, and if the terminals were welded even in that condition, tensile strength at the connected portion would be insufficient. According to the throttle position sensor proposed in the Utility Model No. 2586838, therefore, the improved sensor has been proposed. However, the base plate is connected to the connector terminals through the connecting terminals, and the resistance welding is still required. Those connecting terminals do not meet requirements for easily manufacturing and minimizing the sensor. Also, it is difficult to improve the working efficiency in manufacturing the sensor, because sputtering may cause deficiency in electrical connection between resistors of the circuit and brushes, when the connecting terminals are welded.
According to the rotating position detecting device disclosed in Japanese Patent Laid-open Publication No. 8-285516, the terminal plates are adapted to directly contact at their contact portions with the end portion of the resistor circuit surface, so that number of parts are reduced. However, the terminal plates are mounted in the housing, with the contact portions resiliently deformed, so that they are pressed onto the end portion of the resistor circuit surface by the resilient force. Therefore, it is difficult to obtain and maintain the electrical contact between the contact portions of the terminal plates and the resistor circuit surface. Furthermore, since it is required from a structural view point to provide a quite large clearance between the contact portions of the terminal plates and the resistor circuit surface, it is difficult to meet the requirement for minimizing the device.
Accordingly, it is an object of the present invention to provide a rotary position sensor having a base plate with a detection circuit formed thereon, and connector terminals mounted in a housing, with their connecting portions electrically connected to terminal portions of the detection circuit, wherein the connector terminals and the detection circuit are connected properly and easily.
In accomplishing the above and other objects, a rotary position sensor includes a housing, connector terminals mounted in the housing, whose connecting portions are exposed inside of the housing, a base plate mounted in the housing, on which a detection circuit is formed, and a rotor rotated relative to the base plate. The rotor has contacts contacting with the detection circuit and is movable relative thereto. Terminal portions of the detection circuit are exposed on a surface of the base plate, and the terminal portions of the detection circuit are placed to face the connecting portions of the connector terminals. The rotary position sensor also includes a conductive resilient member disposed between the terminal portions of the detection circuit and the connecting portions of the connector terminals, so that the conductive resilient member allows electrical connection only between the terminal portions of the detection circuit and the connecting portions of the connector terminals. The conductive resilient member is electrically conductive in a perpendicular direction to the surface of the base plate, and electrically insulating in a parallel direction to the surface of the base plate.
Preferably, the conductive resilient member includes an anisotropy conductive rubber sheet which has a plurality of conductive wires embedded therein and directed in a perpendicular direction to the surface of the base plate.